McDonald said: "I've tremendously enjoyed the opportunity to help re-establish News at Ten over the last year and to work alongside Julie Etchingham, who is a fantastically talented journalist, but I've made no secret of the fact that I cannot be in the presenter's chair forever.

"Anchoring ITV News' live coverage of a hugely exciting and historic US election seems the opportune moment to leave on a high."

The ITV director of television, Peter Fincham, said: "Sir Trevor McDonald is the leading news broadcaster of his generation and is responsible for many landmark television news moments.

"Whilst I'd like to pay tribute to his work for ITV News and ITN over the last 35 years, I am delighted that he will be staying with the network and working on a range of projects for ITV1."

The ITV News editor-in-chief, David Mannion, added: "I have been fortunate to work with Trevor for many years during which time we have become close friends as well as colleagues."

Austin said: "I am delighted to be joining News at Ten permanently and look forward to working with Julie Etchingham, who is a great journalist, and popular presenter. It is also an honour to follow in the footsteps of Sir Trevor McDonald."

He is used to a dual role as he presented News at Ten's predecessor, the old 10.30pm bulletin.

When News at Ten returned, Austin moved to a roving anchor role and presented on location for big foreign stories but was always seen as McDonald's heir apparent.

News at Ten was relaunched on ITV1 at the start of 2008.

Despite being head-to-head with News at Ten since January, BBC1's 10pm bulletin has gained around 120,000 viewers since this time last year.

The BBC bulletin has averaged around 4.9 million viewers across the year to date, compared with around 2.5 million for News at Ten.

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